Liberian President Samuel Kanyon Doe became virtually a prisoner in the presidential mansion as rebels besieged Monrovia and Doe's 500-man security force refused to let him leave without them. Doe, amidst ethnic warfare which killed tens of thousands of Liberians and caused over 700,000 more to flee the country, was  captured, tortured and killed by the Independent National Patriotic Front of Liberia (INPFL) led by Prince Yormie Johnson on 9 September 1990. The end of the Doe regime only continued the ethnic warfare in Liberia. Click here to read more about the devastating civil war in Liberia from 1989-1996.
References

Global Security, 'Liberia - First Civil War - 1989-1996', from Global Security Military Section, [Online], Available at: www.globalsecurity.org, [Accessed: 23 July 2013]|Britannica Concise Encyclopedia, 'Samuel Kanyon Doe', from Answers, [Online], Available at: www.answers.com, [Accessed: 23 July 2013]